Jean-Baptiste Joseph Fourier was a French mathematician and physicist born in 1768. He is best known for his work on heat transfer and the theory of Fourier series, which breaks down complex periodic functions into simpler sine and cosine waves. This groundbreaking idea has applications in various fields, including signal processing, acoustics, and image analysis. Fourier's most famous work, "Théorie analytique de la chaleur," published in 1822, laid the foundation for modern thermal analysis. His contributions helped scientists understand how heat moves through different materials, influencing both thermodynamics and engineering. Fourier's legacy continues to impact many areas of science and technology today.